Scientific Consensus as Persuasion

In my previous post I talked about scientific consensus being irrelevant to the process of science. So the question is, should scientific consensus be irrelevant to us as well? The short answer is that if there’s a true consensus, the consensus opinion should carry some weight as a point of persuasion. It would be silly for a person who isn’t an expert in physics to walk around denying the theories of General Relativity or Quantum Mechanics. And, while it’s a logical fallacy to say Quantum Theory is an accurate description of reality just because every respectable physicist I know thinks so, as a point of persuasion it’s pretty darn good.

Having said that, it’s important to realize that all consensus are not equal. Some, like those surrounding the theories of General Relativity and Quantum Mechanics, have been around a long time and have survived enumerable experimental challenges. On the other hand, the vast majority of scientific belief is based on incomplete understanding and over time these beliefs, many of them a scientific consensus at some point, have been proven to be false. A wise person would not give a relatively new scientific consensus about a relatively new theory as much persuasive weight as they would an established and well-tested theory like the General Theory of Relativity.

It is also important to realize that true scientific consensus is hard to come by. Journalists and politicians are quick to claim scientific consensus as they seek to persuade, but it is very hard to establish if there really is a true consensus on a given topic. We could attempt to poll the scientific community and obtain a snapshot of what scientists believe but what would that tell us? What if 80% of scientists think one thing and 20% think another? How tied are these 80% to their beliefs and what part of the 80% really know what they are talking about? How many in the 80% have funding that depends on certain lines of investigation where the consensus opinion is assumed true? What if some of the contrary 20% are top people in the field in question? One could claim a consensus but would it be true consensus?

The last thing to realize is that scientific consensus is volatile. One solid experiment or observation that produces results contrary to a theory and the consensus behind that theory would probably evaporate. The theory in question may still retain some support but a majority of scientists would switch to a position of withholding judgment or even skepticism – the natural state of a scientist.

Regarding the theory of Global Warming due to greenhouse gasses. If there really is a scientific consensus, it definitely falls in the category of a new consensus about a new theory and as such should not be given much weight yet. And frankly, given our current relatively poor understanding about many of the processes involved in climate change, I seriously doubt there is a true consensus among scientists. I think what we really have is a consensus among politicians and journalists. There just isn’t enough solid science behind the theory of global warming yet for anyone with a naturally skeptical bent to be that tied to the theory. There certainly isn’t a consensus among the scientists that I know.